The present invention concerns a tubular heat exchanger comprising tubes for transporting a liquid heat transfer medium between two collecting chambers, and lamellar baffles, maintained on the tubes essentially perpendicular thereto and in close proximity to one another, for intercepting a gaseous heat transfer medium flowing past the tubes .
Tubular heat exchangers of the above-described type have conventionally been used, for example, as automobile radiators. Such heat exchangers, which may be produced of light metal, comprise a plurality of tubes transporting the cooling water between two radiator tanks, the tubes being arranged transversely to the direction of flow of the cooling air. In order to increase the air-side heat transfer, fins in form of thin-walled lamellar air baffles are mounted on the tubes to intercept the cooling air. These baffles are superimposed in close proximity one above the other to form a "stack" of fins along the tubes.
Following the conventional designs of such heat exchangers, the tubes are arranged in two or more rows, one behind the other, and the baffles are correspondingly constructed in form of an elongated rectangle with passages for the tubes arranged in rows. The stacked baffles are maintained in spaced relation by the collars produced at the passages, and also by bent-up projections produced by so-called "tear holes".
In a heat exchanger designed in this manner, the cooling air action in the first tube row is quite favorable with regard to both the flow conditions and the temperature level. However, in the subsequent rows of tubes which follow, these conditions become increasingly unfavorable. This is due to the fact that the subsequent rows of tubes are placed, at least in part, leeward of the first row of tubes so that the cooling air does not impinge directly on the face of each tube. Moreover, due to the increasing temperature of the air as it flows through the heat exchanger, the temperature difference relative to the cooling water decreases so that, seen as a whole, the heat transfer is less favorable in the rear rows of tubes. Finally, the stack of baffles is comparatively deep, due to the necessary distance between the rows of tubes, so that considerable material is required for the baffles themselves.
It is therefore an object of the invention to provide a tubular heat exchanger of the aforementioned type which, for a given number of tubes, facilitates an improved air flow and thereby a more uniform heat transfer among the individual tubes and permits a reduction of the structural depth in the air flow direction.